Transition metal complexes are used as catalysts for many organic reactions. Typically, ligands in the transition metal complexes have been selected empirically, based on experience, from a multitude of molecules wherein the donor atoms in the ligand are generally the same element. Several patents describe automated catalyst selection and evaluation systems that may be used to screen a multiplicity of variations in transition metal and catalyst compositions. Changes in catalytic capabilities, including reactivity, solubility and stability, have generally been accomplished merely by modifying the skeletal structure or the donor/acceptor properties of the substituents attached to skeleton of a known functional ligand. While this approach has provided a multitude of useful catalytic materials, there has been a limitation on the ability to tailor a transition metal catalyst for optimum performance in a broad range of reaction environments, for example, ionic, acidic, basic or aqueous systems. To compensate for the lack of understanding of transition metal ligand interactions and functionality, many transition metal complexes must be used in conjunction with co-catalysts to modify the reaction environment or to affect the properties of the complex to allow for an efficient catalytic cycle. In many such dual entity catalytic systems, the co-catalyst and ligand work in conjunction with the transition metal to form an active catalytic complex by modifying the environment of the transition metal thereby modifying and stabilizing certain fundamental properties of the catalyst.
One catalytic reaction process that uses catalytic transition metal complexes is ATRP. The ATRP equilibrium can be expressed as:

The overall equilibrium constant for ATRP can be expressed as the product of the equilibrium constants for electron transfer between metal complex (KET), electron affinity of the halogen (KEA), bond homolysis of the alkyl halide (KBH) and heterolytic cleavage of the CUII-X bond or “halogen philicity” (KHP). Therefore, for a given alkyl halide R—X, more reducing catalysts will increase KATRP only if KHP stays constant.
Atom Transfer (Overall Equilibrium)
                                                                                                              R                    ⁢                                                                                  ⁢                    —                    ⁢                                                                                  ⁢                    X                                    +                                                            Cu                      I                                        ⁢                    —                    ⁢                                                                                  ⁢                    Y                    ⁢                                          /                                        ⁢                    Ligand                                                  ⁢                                                      ↼                                          k                      d                                                                            ⇀                                          k                      a                                                                      ⁢                                                      R                    •                                    +                                      X                    ⁢                                                                                  ⁢                                                                  —                        ⁢                        Cu                                            II                                        ⁢                    —                    ⁢                                                                                  ⁢                    Y                    ⁢                                          /                                        ⁢                    Ligand                                                              _                                                                          Contributing              ⁢                                                          ⁢              Reactions                                                                                                            Cu                  I                                ⁢                —                ⁢                                                                  ⁢                Y                ⁢                                  /                                ⁢                Ligand                            ⁢                              ⇌                                  K                  ET                                            ⁢                                                                    Cu                    II                                    ⁢                  —                  ⁢                                                                          ⁢                  Y                  ⁢                                      /                                    ⁢                  Ligand                                +                                  e                  ⊖                                                                                                                                          X                  •                                +                                  e                  ⊖                                            ⁢                              ⇌                                  K                  EA                                            ⁢                              X                ⊖                                                                                                        R                ⁢                                                                  ⁢                —                ⁢                                                                  ⁢                X                            ⁢                              ⇌                                  K                  BH                                            ⁢                                                R                  •                                +                                  X                  •                                                                                                                                          X                  ⊖                                +                                                      Cu                    II                                    ⁢                  —                  ⁢                                                                          ⁢                  Y                  ⁢                                      /                                    ⁢                  Ligand                                            ⁢                              ⇌                                  K                  HP                                            ⁢                              X                ⁢                                                                  ⁢                                                      —                    ⁢                    Cu                                    II                                ⁢                —                ⁢                                                                  ⁢                Y                ⁢                                  /                                ⁢                Ligand                                                                                                                  K          ATRP                =                                            k              a                                      k              d                                =                                                    K                EA                            ⁢                              K                BH                            ⁢                              K                HP                            ⁢                              K                ET                            ⁢                                                          ⁢              or              ⁢                                                          ⁢                                                K                  ATRP                                                                      K                    EA                                    ⁢                                      K                    BH                                                                        =                                          K                ET                            ⁢                              K                HP                                                                        (        1        )            
ATRP has been discussed in detail in commonly assigned U.S. Pat. Nos. 5,807,937; 5,789,487; 5,910,549; 5,763,548; 5,789,489; 6,111,022; 6,124,411; 6,162,882; 6,407,187; 6,624,262; and 6,538,091; and U.S. patent application Ser. No. 09/534,827; 09/972,046, now U.S. Pat. No. 6,627,314; Ser. No. 09/972,260, now U.S. Pat. No. 6,624,262; Ser. No. 10/625,890, now abandoned, and Ser. No. 10/034,908, now U.S. Pat. No. 7,049,373, the entire contents of which are hereby incorporated herein by reference. U.S. patent application Ser. No. 10/271,025, now U.S. Pat. No. 6,759,491, describes the Simultaneous Reverse and Normal Initiation (SR&NI) process of ATRP that is used in to initiate a polymerization processes in the Examples. U.S. Pat. No. 6,624,262 discloses fundamental parameters that should be considered when attempting to avoid disproportionation. Disproportionation of the higher oxidation state of the catalyst was reduced in U.S. Pat. No. 6,624,262 by an addition of excess ligands to modify the catalyst environment.
Ligands combining different donor atoms from ligands comprising only one type of donor atom has been previously disclosed. For example, the abstract from Brookhart in PMSE Boston Preprints 87, 59, 2002 discloses the preparation and use of bulky bidentate ligands comprising P with N or S or O donor atoms for olefin polymerization in the gaseous phase. No fundamental reason for selection of the donor atom is provided in the abstract. Also, in Polymer Preprints 2002, 43(2), 3, Sawamoto describes the use of ligands comprising phosphorous and nitrogen. These atoms are known to work together in conjunction with ruthenium as suitable counterion/ligand donor atoms for metal mediated polymerization for the polymerization of neutral nonionic organic monomers. Disclosed is an increase in catalytic activity of the ruthenium complexes via varying ligand-design strategies. Specific discussed were half-metallocene complexes with an electron-donating ligand; ruthenium complexes with a P, N-chelating ligand; and cationic ruthenium complexes with a weakly coordinating anion. The ruthenium complex with a heterodonor ligand was used in a typical organic medium and the only effect noted was an increase in the rate of polymerization that was attributed to improved interaction of the amino donor group compared to amine group. The sole complex also had a lower redox potential than Ru(Cp*)Cl(PPh3)2 (E1/2=0.26V vs 0.46V) and therefore induced more efficient polymerizations of MMA.
PCT publication WO 0151529 describes procatalysts comprising bidentate ligands, catalyst systems, and use in olefin polymerization. The catalyst system comprises a transition metal complex and an alkyl aluminum compound. The transition metal complex will not operate without the alkyl aluminum activator in this dual entity catalyst system. The bidentate ligand is bound to the transition metal by two atoms selected from the group consisting of oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony, and bismuth, or mixtures thereof. However, the catalysts are limited to transition metal comprising titanium, zirconium and hafnium.
PCT publication WO 0187996, (2001) also describes an olefin polymerization catalyst and process and polymer, polymer derivatives, lubricants and fuels thereof. The catalyst described is one having a nitrogen coordinating group and a second coordinating group selected from oxygen, sulfur, selenium and tellurium groups and a metal compd where the metal is a transition metal, boron, aluminum, germanium or tin. The ligands are bidentate ligands and require two carbon atoms as spacers between the donor atoms.
There have been several instances in the prior art inorganic chemistry literature where papers include the description of preparation of transition metal complexes with heterodonor ligands although no utility was described. [Leung, P-H, A Liu, K F Mok, A J P White and D J Williams (1999) “Synthesis and coordination chemistry of a 14-membered macrocyclic ligand containing one phosphorus, two sulfur and one ambidentate sulfoxide donor sets.” Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry(8): 1277-1282. El-Sawaf, A K, D X West, F A El-Saied and R M El-Bahnasawy (1997). “Iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 4-formylantipyrine thiosemicarbazone.” Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry 27(8): 1127-1147. Certi Mazza, M T, L De Cicco, G De Rosa, R De Rosa and R Caramazza (1996). “Preparation and activity of complexes of transition metals and thiolic heterocyclic ligands.” Bollettino—Societa Italiana Biologia Sperimentale 72(3-4): 79-86.] These disclosures provide useful data and properties of transition metal complexes. In the latter paper the chemistry of complexes with thiolic heterocyclic ligands based on the metals binding precisely to the sulphur atom is discussed. Studies were consequently carried out on complexes with thiolic ligands, such as: 2-imidazolidine-thione (IMT), hydantoin (ID), 2-thiohydantoin (TIOID), rhodanine (RD), 2-mercaptoimidazole (MI), 2-mercapto-1-methylimidazole (MMI) and 2-mercaptopyridine (MPYR), which supposed that the co-ordination bond between sulphur and metal is stronger than the possible bond between nitrogen or oxygen and metal due to the minor difference in electronegativity existing between sulphur and metal compared with that existing between nitrogen or oxygen and metal.
Other descriptions and properties of metal complexes with heterodonor ligands may also be found. Jha, R R, D K Sircar, Sadanand and U Jha (1994). “Mixed ligand complexes of bivalent metal ions with 4-amino-5-mercapto-3-methyl-1,2,4-triazole and glycine/alanine.” Asian J Chem 6(3): 468-471. Khalil, M M and A H H Elghandour (1993). “Potentiometric studies on the mixed ligand complexes of copper(II), cobalt(II), nickel(II) and zinc(II) with 1-phenyl-3-cinnamoylthiourea and secondary ligands containing oxygen, nitrogen or sulfur as donor atoms.” Bull Fac Pharm (Cairo Univ) 31(3): 465-469 and Bernhardt, P V and P Comba (1992). “Molecular mechanics calculations of transition metal complexes.” Inorg Chem 31(12): 2638-2644.